Spurs forward Matt Bonner, a member of the National Basketball Players Association’s executive committee, said Sunday the union’s leadership has scheduled a conference call for Monday to discuss its next move.

The NBA late Saturday night gave the union a formal proposal for a new collective bargaining agreement that Bonner said called for “basically another 50-50 split” of basketball related income, along with some changes in the luxury tax system he said represented little change from the owners’ prior positions.

The union rejected the offer on the spot, whereupon Commissioner David Stern said it would remain only through the end of business on Wednesday.

If not accepted by the close of business Wednesday, Stern said the offer would be withdrawn and replaced by a much worse deal, with a revenue split giving the players only 47 percnet of BRI and a “flex” salary cap the players already have characterized as an unacceptable hard cap.

Lakers guard Derek Fisher, the union’s president, said the NBA deal was not one the executive committee could take to its players for a vote and Bonner said every member of the executive committee is behind the decision to reject it.

“We’re all on the same page,” he said.

Bonner described the frustration of Saturday’s session, which was conducted under the guidance of George Cohen, head of the Federal Mediation and Conciliation Service.

“Saturday sucked,” he said. “The way we saw of saving the season and getting a deal was by saying the system was more important to us, BRI more important to them; we can compromise on BRI if they can come more to us on the remaining system issues.

“That’s what we were hoping would get a deal and we really thought the approach we took was going to get it done. But when George came back after taking our offer to the owners, what he came back with was five or six changes in system things, and all but one were what the owners wanted. It was basically their deal.”

Bonner said the executive would discuss all aspects of the impasse in its Monday conference call, including a move by some agents to collect enough player names on petitions to call for a vote that could decertify the union.

Decertification would allow players to file an anti-trust lawsuit against the league, but the more important immediate result would be some leverage for the union during roughly 45 days it would take for the National Labor Relations Board to arrange a vote of all 450 members of the union.

The threat of decertification and the uncertainty that comes with it could give the union the leverage it needs to coax a better offer from the league than the deal it rejected Saturday.